1. Field of the Invention
The invention concerns an embossing foil, in particular a hot embossing foil, preferably for the production of motor vehicle licence plates, comprising a carrier film and a transfer layer means which is detachable therefrom and which--starting from the carrier film--includes a transparent protective lacquer layer, at least one colored lacquer layer and an adhesive layer, which is possibly formed by the colored lacquer layer, for fixing the transfer layer means on a substrate to be decorated, for example the carrier plate of a motor vehicle licence plate.
2. Description of the Prior Art
It is known for motor vehicle licence or registration plates to be produced using hot embossing foils, wherein single-colored hot embossing foils are used to produce the background or undercoat lacquer layer or the lacquer layer which is different therefrom, for the characters on the licence plate, for example letters, figures, coats of arms, etc. Licence plates of that kind are distinguished over the hitherto conventional licence plates on the one hand by a high degree of durability and on the other hand by virtue of the fact that special safety measures during production can be avoided, because operation no longer involves liquid lacquers. The embossing foil wastes after the operation of embossing the licence plates can be disposed of without difficulty and in particular in a satisfactory and acceptable fashion.
Now, in particular having regard to the number of vehicle thefts which have increased greatly in recent times, and the forged licence plates which are used to a large extent in that respect, it would be desirable to provide an embossing foil which makes it possible to provide the licence plates with particular characters which make forgery difficult, while in addition the aim is to afford the option of establishing in a simple manner and by means of mechanical devices whether the licence plate is or is not a forged licence plate.
In DE-31 51 012, there is disclosed a method of identifying articles of value, for example, pictures, porcelain or articles of wood, in which a marking is applied to suitable locations on the surface, by means of dyes which are visible only when viewed under UV-radiation, employing an optical brightener and/or an almost colorless fluorescent dye. In the known method, the dyes are applied by hand and the marking must be additionally fixed with a cover layer of a cross-linkable polymer. That procedure is not possible, for example, in regard to the production of motor vehicle identifications because it would involve much too much cost. In addition, it is normally not possible for machine-readable graphic elements to be applied manually. A particularly serious disadvantage of the known method; however, is that it appears impossible for the cover layer to be applied for fixing the UV-visible marking to be applied so uniformly that any attempt at removal of the UV-readable marking can at any event be detected.